Lib/idlelib/editor.py

import importlib.abc
import importlib.util
import os
import platform
import re
import string
import sys
import tokenize
import traceback
import webbrowser

from tkinter import *
from tkinter.font import Font
from tkinter.ttk import Scrollbar
import tkinter.simpledialog as tkSimpleDialog
import tkinter.messagebox as tkMessageBox

from idlelib.config import idleConf
from idlelib import configdialog
from idlelib import grep
from idlelib import help
from idlelib import help_about
from idlelib import macosx
from idlelib.multicall import MultiCallCreator
from idlelib import pyparse
from idlelib import query
from idlelib import replace
from idlelib import search
from idlelib import window

# The default tab setting for a Text widget, in average-width characters.
TK_TABWIDTH_DEFAULT = 8
_py_version = ' (%s)' % platform.python_version()
darwin = sys.platform == 'darwin'

def _sphinx_version():
    "Format sys.version_info to produce the Sphinx version string used to install the chm docs"
    major, minor, micro, level, serial = sys.version_info
    release = '%s%s' % (major, minor)
    release += '%s' % (micro,)
    if level == 'candidate':
        release += 'rc%s' % (serial,)
    elif level != 'final':
        release += '%s%s' % (level[0], serial)
    return release


class EditorWindow(object):
    from idlelib.percolator import Percolator
    from idlelib.colorizer import ColorDelegator, color_config
    from idlelib.undo import UndoDelegator
    from idlelib.iomenu import IOBinding, encoding
    from idlelib import mainmenu
    from idlelib.statusbar import MultiStatusBar
    from idlelib.autocomplete import AutoComplete
    from idlelib.autoexpand import AutoExpand
    from idlelib.calltip import Calltip
    from idlelib.codecontext import CodeContext
    from idlelib.sidebar import LineNumbers
    from idlelib.format import FormatParagraph, FormatRegion, Indents, Rstrip
    from idlelib.parenmatch import ParenMatch
    from idlelib.squeezer import Squeezer
    from idlelib.zoomheight import ZoomHeight

    filesystemencoding = sys.getfilesystemencoding()  # for file names
    help_url = None

    allow_code_context = True
    allow_line_numbers = True

    def __init__(self, flist=None, filename=None, key=None, root=None):
        # Delay import: runscript imports pyshell imports EditorWindow.
        from idlelib.runscript import ScriptBinding

        if EditorWindow.help_url is None:
            dochome =  os.path.join(sys.base_prefix, 'Doc', 'index.html')
            if sys.platform.count('linux'):
                # look for html docs in a couple of standard places
                pyver = 'python-docs-' + '%s.%s.%s' % sys.version_info[:3]
                if os.path.isdir('/var/www/html/python/'):  # "python2" rpm
                    dochome = '/var/www/html/python/index.html'
                else:
                    basepath = '/usr/share/doc/'  # standard location
                    dochome = os.path.join(basepath, pyver,
                                           'Doc', 'index.html')
            elif sys.platform[:3] == 'win':
                chmfile = os.path.join(sys.base_prefix, 'Doc',
                                       'Python%s.chm' % _sphinx_version())
                if os.path.isfile(chmfile):
                    dochome = chmfile
            elif sys.platform == 'darwin':
                # documentation may be stored inside a python framework
                dochome = os.path.join(sys.base_prefix,
                        'Resources/English.lproj/Documentation/index.html')
            dochome = os.path.normpath(dochome)
            if os.path.isfile(dochome):
                EditorWindow.help_url = dochome
                if sys.platform == 'darwin':
                    # Safari requires real file:-URLs
                    EditorWindow.help_url = 'file://' + EditorWindow.help_url
            else:
                EditorWindow.help_url = ("https://docs.python.org/%d.%d/"
                                         % sys.version_info[:2])
        self.flist = flist
        root = root or flist.root
        self.root = root
        self.menubar = Menu(root)
        self.top = top = window.ListedToplevel(root, menu=self.menubar)
        if flist:
            self.tkinter_vars = flist.vars
            #self.top.instance_dict makes flist.inversedict available to
            #configdialog.py so it can access all EditorWindow instances
            self.top.instance_dict = flist.inversedict
        else:
            self.tkinter_vars = {}  # keys: Tkinter event names
                                    # values: Tkinter variable instances
            self.top.instance_dict = {}
        self.recent_files_path = os.path.join(
                idleConf.userdir, 'recent-files.lst')

        self.prompt_last_line = ''  # Override in PyShell
        self.text_frame = text_frame = Frame(top)
        self.vbar = vbar = Scrollbar(text_frame, name='vbar')
        width = idleConf.GetOption('main', 'EditorWindow', 'width', type='int')
        text_options = {
                'name': 'text',
                'padx': 5,
                'wrap': 'none',
                'highlightthickness': 0,
                'width': width,
                'tabstyle': 'wordprocessor',  # new in 8.5
                'height': idleConf.GetOption(
                        'main', 'EditorWindow', 'height', type='int'),
                }
        self.text = text = MultiCallCreator(Text)(text_frame, **text_options)
        self.top.focused_widget = self.text

        self.createmenubar()
        self.apply_bindings()

        self.top.protocol("WM_DELETE_WINDOW", self.close)
        self.top.bind("<<close-window>>", self.close_event)
        if macosx.isAquaTk():
            # Command-W on editor windows doesn't work without this.
            text.bind('<<close-window>>', self.close_event)
            # Some OS X systems have only one mouse button, so use
            # control-click for popup context menus there. For two
            # buttons, AquaTk defines <2> as the right button, not <3>.
            text.bind("<Control-Button-1>",self.right_menu_event)
            text.bind("<2>", self.right_menu_event)
        else:
            # Elsewhere, use right-click for popup menus.
            text.bind("<3>",self.right_menu_event)
        text.bind('<MouseWheel>', self.mousescroll)
        text.bind('<Button-4>', self.mousescroll)
        text.bind('<Button-5>', self.mousescroll)
        text.bind('<Configure>', self.handle_winconfig)
        text.bind("<<cut>>", self.cut)
        text.bind("<<copy>>", self.copy)
        text.bind("<<paste>>", self.paste)
        text.bind("<<center-insert>>", self.center_insert_event)
        text.bind("<<help>>", self.help_dialog)
        text.bind("<<python-docs>>", self.python_docs)
        text.bind("<<about-idle>>", self.about_dialog)
        text.bind("<<open-config-dialog>>", self.config_dialog)
        text.bind("<<open-module>>", self.open_module_event)
        text.bind("<<do-nothing>>", lambda event: "break")
        text.bind("<<select-all>>", self.select_all)
        text.bind("<<remove-selection>>", self.remove_selection)
        text.bind("<<find>>", self.find_event)
        text.bind("<<find-again>>", self.find_again_event)
        text.bind("<<find-in-files>>", self.find_in_files_event)
        text.bind("<<find-selection>>", self.find_selection_event)
        text.bind("<<replace>>", self.replace_event)
        text.bind("<<goto-line>>", self.goto_line_event)
        text.bind("<<smart-backspace>>",self.smart_backspace_event)
        text.bind("<<newline-and-indent>>",self.newline_and_indent_event)
        text.bind("<<smart-indent>>",self.smart_indent_event)
        self.fregion = fregion = self.FormatRegion(self)
        # self.fregion used in smart_indent_event to access indent_region.
        text.bind("<<indent-region>>", fregion.indent_region_event)
        text.bind("<<dedent-region>>", fregion.dedent_region_event)
        text.bind("<<comment-region>>", fregion.comment_region_event)
        text.bind("<<uncomment-region>>", fregion.uncomment_region_event)
        text.bind("<<tabify-region>>", fregion.tabify_region_event)
        text.bind("<<untabify-region>>", fregion.untabify_region_event)
        text.bind("<<toggle-tabs>>", self.Indents.toggle_tabs_event)
        text.bind("<<change-indentwidth>>", self.Indents.change_indentwidth_event)
        text.bind("<Left>", self.move_at_edge_if_selection(0))
        text.bind("<Right>", self.move_at_edge_if_selection(1))
        text.bind("<<del-word-left>>", self.del_word_left)
        text.bind("<<del-word-right>>", self.del_word_right)
        text.bind("<<beginning-of-line>>", self.home_callback)

        if flist:
            flist.inversedict[self] = key
            if key:
                flist.dict[key] = self
            text.bind("<<open-new-window>>", self.new_callback)
            text.bind("<<close-all-windows>>", self.flist.close_all_callback)
            text.bind("<<open-class-browser>>", self.open_module_browser)
            text.bind("<<open-path-browser>>", self.open_path_browser)
            text.bind("<<open-turtle-demo>>", self.open_turtle_demo)

        self.set_status_bar()
        text_frame.pack(side=LEFT, fill=BOTH, expand=1)
        text_frame.rowconfigure(1, weight=1)
        text_frame.columnconfigure(1, weight=1)
        vbar['command'] = self.handle_yview
        vbar.grid(row=1, column=2, sticky=NSEW)
        text['yscrollcommand'] = vbar.set
        text['font'] = idleConf.GetFont(self.root, 'main', 'EditorWindow')
        text.grid(row=1, column=1, sticky=NSEW)
        text.focus_set()
        self.set_width()

        # usetabs true  -> literal tab characters are used by indent and
        #                  dedent cmds, possibly mixed with spaces if
        #                  indentwidth is not a multiple of tabwidth,
        #                  which will cause Tabnanny to nag!
        #         false -> tab characters are converted to spaces by indent
        #                  and dedent cmds, and ditto TAB keystrokes
        # Although use-spaces=0 can be configured manually in config-main.def,
        # configuration of tabs v. spaces is not supported in the configuration
        # dialog.  IDLE promotes the preferred Python indentation: use spaces!
        usespaces = idleConf.GetOption('main', 'Indent',
                                       'use-spaces', type='bool')
        self.usetabs = not usespaces

        # tabwidth is the display width of a literal tab character.
        # CAUTION:  telling Tk to use anything other than its default
        # tab setting causes it to use an entirely different tabbing algorithm,
        # treating tab stops as fixed distances from the left margin.
        # Nobody expects this, so for now tabwidth should never be changed.
        self.tabwidth = 8    # must remain 8 until Tk is fixed.

        # indentwidth is the number of screen characters per indent level.
        # The recommended Python indentation is four spaces.
        self.indentwidth = self.tabwidth
        self.set_notabs_indentwidth()

        # When searching backwards for a reliable place to begin parsing,
        # first start num_context_lines[0] lines back, then
        # num_context_lines[1] lines back if that didn't work, and so on.
        # The last value should be huge (larger than the # of lines in a
        # conceivable file).
        # Making the initial values larger slows things down more often.
        self.num_context_lines = 50, 500, 5000000
        self.per = per = self.Percolator(text)
        self.undo = undo = self.UndoDelegator()
        per.insertfilter(undo)
        text.undo_block_start = undo.undo_block_start
        text.undo_block_stop = undo.undo_block_stop
        undo.set_saved_change_hook(self.saved_change_hook)
        # IOBinding implements file I/O and printing functionality
        self.io = io = self.IOBinding(self)
        io.set_filename_change_hook(self.filename_change_hook)
        self.good_load = False
        self.set_indentation_params(False)
        self.color = None # initialized below in self.ResetColorizer
        self.code_context = None # optionally initialized later below
        self.line_numbers = None # optionally initialized later below
        if filename:
            if os.path.exists(filename) and not os.path.isdir(filename):
                if io.loadfile(filename):
                    self.good_load = True
                    is_py_src = self.ispythonsource(filename)
                    self.set_indentation_params(is_py_src)
            else:
                io.set_filename(filename)
                self.good_load = True

        self.ResetColorizer()
        self.saved_change_hook()
        self.update_recent_files_list()
        self.load_extensions()
        menu = self.menudict.get('window')
        if menu:
            end = menu.index("end")
            if end is None:
                end = -1
            if end >= 0:
                menu.add_separator()
                end = end + 1
            self.wmenu_end = end
            window.register_callback(self.postwindowsmenu)

        # Some abstractions so IDLE extensions are cross-IDE
        self.askyesno = tkMessageBox.askyesno
        self.askinteger = tkSimpleDialog.askinteger
        self.showerror = tkMessageBox.showerror

        # Add pseudoevents for former extension fixed keys.
        # (This probably needs to be done once in the process.)
        text.event_add('<<autocomplete>>', '<Key-Tab>')
        text.event_add('<<try-open-completions>>', '<KeyRelease-period>',
                       '<KeyRelease-slash>', '<KeyRelease-backslash>')
        text.event_add('<<try-open-calltip>>', '<KeyRelease-parenleft>')
        text.event_add('<<refresh-calltip>>', '<KeyRelease-parenright>')
        text.event_add('<<paren-closed>>', '<KeyRelease-parenright>',
                       '<KeyRelease-bracketright>', '<KeyRelease-braceright>')

        # Former extension bindings depends on frame.text being packed
        # (called from self.ResetColorizer()).
        autocomplete = self.AutoComplete(self)
        text.bind("<<autocomplete>>", autocomplete.autocomplete_event)
        text.bind("<<try-open-completions>>",
                  autocomplete.try_open_completions_event)
        text.bind("<<force-open-completions>>",
                  autocomplete.force_open_completions_event)
        text.bind("<<expand-word>>", self.AutoExpand(self).expand_word_event)
        text.bind("<<format-paragraph>>",
                  self.FormatParagraph(self).format_paragraph_event)
        parenmatch = self.ParenMatch(self)
        text.bind("<<flash-paren>>", parenmatch.flash_paren_event)
        text.bind("<<paren-closed>>", parenmatch.paren_closed_event)
        scriptbinding = ScriptBinding(self)
        text.bind("<<check-module>>", scriptbinding.check_module_event)
        text.bind("<<run-module>>", scriptbinding.run_module_event)
        text.bind("<<run-custom>>", scriptbinding.run_custom_event)
        text.bind("<<do-rstrip>>", self.Rstrip(self).do_rstrip)
        ctip = self.Calltip(self)
        text.bind("<<try-open-calltip>>", ctip.try_open_calltip_event)
        #refresh-calltip must come after paren-closed to work right
        text.bind("<<refresh-calltip>>", ctip.refresh_calltip_event)
        text.bind("<<force-open-calltip>>", ctip.force_open_calltip_event)
        text.bind("<<zoom-height>>", self.ZoomHeight(self).zoom_height_event)
        if self.allow_code_context:
            self.code_context = self.CodeContext(self)
            text.bind("<<toggle-code-context>>",
                      self.code_context.toggle_code_context_event)
        else:
            self.update_menu_state('options', '*Code Context', 'disabled')
        if self.allow_line_numbers:
            self.line_numbers = self.LineNumbers(self)
            if idleConf.GetOption('main', 'EditorWindow',
                                  'line-numbers-default', type='bool'):
                self.toggle_line_numbers_event()
            text.bind("<<toggle-line-numbers>>", self.toggle_line_numbers_event)
        else:
            self.update_menu_state('options', '*Line Numbers', 'disabled')

    def handle_winconfig(self, event=None):
        self.set_width()

    def set_width(self):
        text = self.text
        inner_padding = sum(map(text.tk.getint, [text.cget('border'),
                                                 text.cget('padx')]))
        pixel_width = text.winfo_width() - 2 * inner_padding

        # Divide the width of the Text widget by the font width,
        # which is taken to be the width of '0' (zero).
        # http://www.tcl.tk/man/tcl8.6/TkCmd/text.htm#M21
        zero_char_width = \
            Font(text, font=text.cget('font')).measure('0')
        self.width = pixel_width // zero_char_width

    def _filename_to_unicode(self, filename):
        """Return filename as BMP unicode so displayable in Tk."""
        # Decode bytes to unicode.
        if isinstance(filename, bytes):
            try:
                filename = filename.decode(self.filesystemencoding)
            except UnicodeDecodeError:
                try:
                    filename = filename.decode(self.encoding)
                except UnicodeDecodeError:
                    # byte-to-byte conversion
                    filename = filename.decode('iso8859-1')
        # Replace non-BMP char with diamond questionmark.
        return re.sub('[\U00010000-\U0010FFFF]', '\ufffd', filename)

    def new_callback(self, event):
        dirname, basename = self.io.defaultfilename()
        self.flist.new(dirname)
        return "break"

    def home_callback(self, event):
        if (event.state & 4) != 0 and event.keysym == "Home":
            # state&4==Control. If <Control-Home>, use the Tk binding.
            return None
        if self.text.index("iomark") and \
           self.text.compare("iomark", "<=", "insert lineend") and \
           self.text.compare("insert linestart", "<=", "iomark"):
            # In Shell on input line, go to just after prompt
            insertpt = int(self.text.index("iomark").split(".")[1])
        else:
            line = self.text.get("insert linestart", "insert lineend")
            for insertpt in range(len(line)):
                if line[insertpt] not in (' ','\t'):
                    break
            else:
                insertpt=len(line)
        lineat = int(self.text.index("insert").split('.')[1])
        if insertpt == lineat:
            insertpt = 0
        dest = "insert linestart+"+str(insertpt)+"c"
        if (event.state&1) == 0:
            # shift was not pressed
            self.text.tag_remove("sel", "1.0", "end")
        else:
            if not self.text.index("sel.first"):
                # there was no previous selection
                self.text.mark_set("my_anchor", "insert")
            else:
                if self.text.compare(self.text.index("sel.first"), "<",
                                     self.text.index("insert")):
                    self.text.mark_set("my_anchor", "sel.first") # extend back
                else:
                    self.text.mark_set("my_anchor", "sel.last") # extend forward
            first = self.text.index(dest)
            last = self.text.index("my_anchor")
            if self.text.compare(first,">",last):
                first,last = last,first
            self.text.tag_remove("sel", "1.0", "end")
            self.text.tag_add("sel", first, last)
        self.text.mark_set("insert", dest)
        self.text.see("insert")
        return "break"

    def set_status_bar(self):
        self.status_bar = self.MultiStatusBar(self.top)
        sep = Frame(self.top, height=1, borderwidth=1, background='grey75')
        if sys.platform == "darwin":
            # Insert some padding to avoid obscuring some of the statusbar
            # by the resize widget.
            self.status_bar.set_label('_padding1', '    ', side=RIGHT)
        self.status_bar.set_label('column', 'Col: ?', side=RIGHT)
        self.status_bar.set_label('line', 'Ln: ?', side=RIGHT)
        self.status_bar.pack(side=BOTTOM, fill=X)
        sep.pack(side=BOTTOM, fill=X)
        self.text.bind("<<set-line-and-column>>", self.set_line_and_column)
        self.text.event_add("<<set-line-and-column>>",
                            "<KeyRelease>", "<ButtonRelease>")
        self.text.after_idle(self.set_line_and_column)

    def set_line_and_column(self, event=None):
        line, column = self.text.index(INSERT).split('.')
        self.status_bar.set_label('column', 'Col: %s' % column)
        self.status_bar.set_label('line', 'Ln: %s' % line)

    menu_specs = [
        ("file", "_File"),
        ("edit", "_Edit"),
        ("format", "F_ormat"),
        ("run", "_Run"),
        ("options", "_Options"),
        ("window", "_Window"),
        ("help", "_Help"),
    ]


    def createmenubar(self):
        mbar = self.menubar
        self.menudict = menudict = {}
        for name, label in self.menu_specs:
            underline, label = prepstr(label)
            menudict[name] = menu = Menu(mbar, name=name, tearoff=0)
            mbar.add_cascade(label=label, menu=menu, underline=underline)
        if macosx.isCarbonTk():
            # Insert the application menu
            menudict['application'] = menu = Menu(mbar, name='apple',
                                                  tearoff=0)
            mbar.add_cascade(label='IDLE', menu=menu)
        self.fill_menus()
        self.recent_files_menu = Menu(self.menubar, tearoff=0)
        self.menudict['file'].insert_cascade(3, label='Recent Files',
                                             underline=0,
                                             menu=self.recent_files_menu)
        self.base_helpmenu_length = self.menudict['help'].index(END)
        self.reset_help_menu_entries()

    def postwindowsmenu(self):
        # Only called when Window menu exists
        menu = self.menudict['window']
        end = menu.index("end")
        if end is None:
            end = -1
        if end > self.wmenu_end:
            menu.delete(self.wmenu_end+1, end)
        window.add_windows_to_menu(menu)

    def update_menu_label(self, menu, index, label):
        "Update label for menu item at index."
        menuitem = self.menudict[menu]
        menuitem.entryconfig(index, label=label)

    def update_menu_state(self, menu, index, state):
        "Update state for menu item at index."
        menuitem = self.menudict[menu]
        menuitem.entryconfig(index, state=state)

    def handle_yview(self, event, *args):
        "Handle scrollbar."
        if event == 'moveto':
            fraction = float(args[0])
            lines = (round(self.getlineno('end') * fraction) -
                     self.getlineno('@0,0'))
            event = 'scroll'
            args = (lines, 'units')
        self.text.yview(event, *args)
        return 'break'

    def mousescroll(self, event):
        """Handle scrollwheel event.

        For wheel up, event.delta = 120*n on Windows, -1*n on darwin,
        where n can be > 1 if one scrolls fast.  Flicking the wheel
        generates up to maybe 20 events with n up to 10 or more 1.
        Macs use wheel down (delta = 1*n) to scroll up, so positive
        delta means to scroll up on both systems.

        X-11 sends Control-Button-4 event instead.
        """
        up = {EventType.MouseWheel: event.delta > 0,
              EventType.Button: event.num == 4}
        lines = -5 if up[event.type] else 5
        self.text.yview_scroll(lines, 'units')
        return 'break'

    rmenu = None

    def right_menu_event(self, event):
        self.text.mark_set("insert", "@%d,%d" % (event.x, event.y))
        if not self.rmenu:
            self.make_rmenu()
        rmenu = self.rmenu
        self.event = event
        iswin = sys.platform[:3] == 'win'
        if iswin:
            self.text.config(cursor="arrow")

        for item in self.rmenu_specs:
            try:
                label, eventname, verify_state = item
            except ValueError: # see issue1207589
                continue

            if verify_state is None:
                continue
            state = getattr(self, verify_state)()
            rmenu.entryconfigure(label, state=state)


        rmenu.tk_popup(event.x_root, event.y_root)
        if iswin:
            self.text.config(cursor="ibeam")
        return "break"

    rmenu_specs = [
        # ("Label", "<<virtual-event>>", "statefuncname"), ...
        ("Close", "<<close-window>>", None), # Example
    ]

    def make_rmenu(self):
        rmenu = Menu(self.text, tearoff=0)
        for item in self.rmenu_specs:
            label, eventname = item[0], item[1]
            if label is not None:
                def command(text=self.text, eventname=eventname):
                    text.event_generate(eventname)
                rmenu.add_command(label=label, command=command)
            else:
                rmenu.add_separator()
        self.rmenu = rmenu

    def rmenu_check_cut(self):
        return self.rmenu_check_copy()

    def rmenu_check_copy(self):
        try:
            indx = self.text.index('sel.first')
        except TclError:
            return 'disabled'
        else:
            return 'normal' if indx else 'disabled'

    def rmenu_check_paste(self):
        try:
            self.text.tk.call('tk::GetSelection', self.text, 'CLIPBOARD')
        except TclError:
            return 'disabled'
        else:
            return 'normal'

    def about_dialog(self, event=None):
        "Handle Help 'About IDLE' event."
        # Synchronize with macosx.overrideRootMenu.about_dialog.
        help_about.AboutDialog(self.top)
        return "break"

    def config_dialog(self, event=None):
        "Handle Options 'Configure IDLE' event."
        # Synchronize with macosx.overrideRootMenu.config_dialog.
        configdialog.ConfigDialog(self.top,'Settings')
        return "break"

    def help_dialog(self, event=None):
        "Handle Help 'IDLE Help' event."
        # Synchronize with macosx.overrideRootMenu.help_dialog.
        if self.root:
            parent = self.root
        else:
            parent = self.top
        help.show_idlehelp(parent)
        return "break"

    def python_docs(self, event=None):
        if sys.platform[:3] == 'win':
            try:
                os.startfile(self.help_url)
            except OSError as why:
                tkMessageBox.showerror(title='Document Start Failure',
                    message=str(why), parent=self.text)
        else:
            webbrowser.open(self.help_url)
        return "break"

    def cut(self,event):
        self.text.event_generate("<<Cut>>")
        return "break"

    def copy(self,event):
        if not self.text.tag_ranges("sel"):
            # There is no selection, so do nothing and maybe interrupt.
            return None
        self.text.event_generate("<<Copy>>")
        return "break"

    def paste(self,event):
        self.text.event_generate("<<Paste>>")
        self.text.see("insert")
        return "break"

    def select_all(self, event=None):
        self.text.tag_add("sel", "1.0", "end-1c")
        self.text.mark_set("insert", "1.0")
        self.text.see("insert")
        return "break"

    def remove_selection(self, event=None):
        self.text.tag_remove("sel", "1.0", "end")
        self.text.see("insert")
        return "break"

    def move_at_edge_if_selection(self, edge_index):
        """Cursor move begins at start or end of selection

        When a left/right cursor key is pressed create and return to Tkinter a
        function which causes a cursor move from the associated edge of the
        selection.

        """
        self_text_index = self.text.index
        self_text_mark_set = self.text.mark_set
        edges_table = ("sel.first+1c", "sel.last-1c")
        def move_at_edge(event):
            if (event.state & 5) == 0: # no shift(==1) or control(==4) pressed
                try:
                    self_text_index("sel.first")
                    self_text_mark_set("insert", edges_table[edge_index])
                except TclError:
                    pass
        return move_at_edge

    def del_word_left(self, event):
        self.text.event_generate('<Meta-Delete>')
        return "break"

    def del_word_right(self, event):
        self.text.event_generate('<Meta-d>')
        return "break"

    def find_event(self, event):
        search.find(self.text)
        return "break"

    def find_again_event(self, event):
        search.find_again(self.text)
        return "break"

    def find_selection_event(self, event):
        search.find_selection(self.text)
        return "break"

    def find_in_files_event(self, event):
        grep.grep(self.text, self.io, self.flist)
        return "break"

    def replace_event(self, event):
        replace.replace(self.text)
        return "break"

    def goto_line_event(self, event):
        text = self.text
        lineno = tkSimpleDialog.askinteger("Goto",
                "Go to line number:",parent=text)
        if lineno is None:
            return "break"
        if lineno <= 0:
            text.bell()
            return "break"
        text.mark_set("insert", "%d.0" % lineno)
        text.see("insert")
        return "break"

    def open_module(self):
        """Get module name from user and open it.

        Return module path or None for calls by open_module_browser
        when latter is not invoked in named editor window.
        """
        # XXX This, open_module_browser, and open_path_browser
        # would fit better in iomenu.IOBinding.
        try:
            name = self.text.get("sel.first", "sel.last").strip()
        except TclError:
            name = ''
        file_path = query.ModuleName(
                self.text, "Open Module",
                "Enter the name of a Python module\n"
                "to search on sys.path and open:",
                name).result
        if file_path is not None:
            if self.flist:
                self.flist.open(file_path)
            else:
                self.io.loadfile(file_path)
        return file_path

    def open_module_event(self, event):
        self.open_module()
        return "break"

    def open_module_browser(self, event=None):
        filename = self.io.filename
        if not (self.__class__.__name__ == 'PyShellEditorWindow'
                and filename):
            filename = self.open_module()
            if filename is None:
                return "break"
        from idlelib import browser
        browser.ModuleBrowser(self.root, filename)
        return "break"

    def open_path_browser(self, event=None):
        from idlelib import pathbrowser
        pathbrowser.PathBrowser(self.root)
        return "break"

    def open_turtle_demo(self, event = None):
        import subprocess

        cmd = [sys.executable,
               '-c',
               'from turtledemo.__main__ import main; main()']
        subprocess.Popen(cmd, shell=False)
        return "break"

    def gotoline(self, lineno):
        if lineno is not None and lineno > 0:
            self.text.mark_set("insert", "%d.0" % lineno)
            self.text.tag_remove("sel", "1.0", "end")
            self.text.tag_add("sel", "insert", "insert +1l")
            self.center()

    def ispythonsource(self, filename):
        if not filename or os.path.isdir(filename):
            return True
        base, ext = os.path.splitext(os.path.basename(filename))
        if os.path.normcase(ext) in (".py", ".pyw"):
            return True
        line = self.text.get('1.0', '1.0 lineend')
        return line.startswith('#!') and 'python' in line

    def close_hook(self):
        if self.flist:
            self.flist.unregister_maybe_terminate(self)
            self.flist = None

    def set_close_hook(self, close_hook):
        self.close_hook = close_hook

    def filename_change_hook(self):
        if self.flist:
            self.flist.filename_changed_edit(self)
        self.saved_change_hook()
        self.top.update_windowlist_registry(self)
        self.ResetColorizer()

    def _addcolorizer(self):
        if self.color:
            return
        if self.ispythonsource(self.io.filename):
            self.color = self.ColorDelegator()
        # can add more colorizers here...
        if self.color:
            self.per.removefilter(self.undo)
            self.per.insertfilter(self.color)
            self.per.insertfilter(self.undo)

    def _rmcolorizer(self):
        if not self.color:
            return
        self.color.removecolors()
        self.per.removefilter(self.color)
        self.color = None

    def ResetColorizer(self):
        "Update the color theme"
        # Called from self.filename_change_hook and from configdialog.py
        self._rmcolorizer()
        self._addcolorizer()
        EditorWindow.color_config(self.text)

        if self.code_context is not None:
            self.code_context.update_highlight_colors()

        if self.line_numbers is not None:
            self.line_numbers.update_colors()

    IDENTCHARS = string.ascii_letters + string.digits + "_"

    def colorize_syntax_error(self, text, pos):
        text.tag_add("ERROR", pos)
        char = text.get(pos)
        if char and char in self.IDENTCHARS:
            text.tag_add("ERROR", pos + " wordstart", pos)
        if '\n' == text.get(pos):   # error at line end
            text.mark_set("insert", pos)
        else:
            text.mark_set("insert", pos + "+1c")
        text.see(pos)

    def ResetFont(self):
        "Update the text widgets' font if it is changed"
        # Called from configdialog.py

        # Update the code context widget first, since its height affects
        # the height of the text widget.  This avoids double re-rendering.
        if self.code_context is not None:
            self.code_context.update_font()
        # Next, update the line numbers widget, since its width affects
        # the width of the text widget.
        if self.line_numbers is not None:
            self.line_numbers.update_font()
        # Finally, update the main text widget.
        new_font = idleConf.GetFont(self.root, 'main', 'EditorWindow')
        self.text['font'] = new_font
        self.set_width()

    def RemoveKeybindings(self):
        "Remove the keybindings before they are changed."
        # Called from configdialog.py
        self.mainmenu.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
        for event, keylist in keydefs.items():
            self.text.event_delete(event, *keylist)
        for extensionName in self.get_standard_extension_names():
            xkeydefs = idleConf.GetExtensionBindings(extensionName)
            if xkeydefs:
                for event, keylist in xkeydefs.items():
                    self.text.event_delete(event, *keylist)

    def ApplyKeybindings(self):
        "Update the keybindings after they are changed"
        # Called from configdialog.py
        self.mainmenu.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
        self.apply_bindings()
        for extensionName in self.get_standard_extension_names():
            xkeydefs = idleConf.GetExtensionBindings(extensionName)
            if xkeydefs:
                self.apply_bindings(xkeydefs)
        #update menu accelerators
        menuEventDict = {}
        for menu in self.mainmenu.menudefs:
            menuEventDict[menu[0]] = {}
            for item in menu[1]:
                if item:
                    menuEventDict[menu[0]][prepstr(item[0])[1]] = item[1]
        for menubarItem in self.menudict:
            menu = self.menudict[menubarItem]
            end = menu.index(END)
            if end is None:
                # Skip empty menus
                continue
            end += 1
            for index in range(0, end):
                if menu.type(index) == 'command':
                    accel = menu.entrycget(index, 'accelerator')
                    if accel:
                        itemName = menu.entrycget(index, 'label')
                        event = ''
                        if menubarItem in menuEventDict:
                            if itemName in menuEventDict[menubarItem]:
                                event = menuEventDict[menubarItem][itemName]
                        if event:
                            accel = get_accelerator(keydefs, event)
                            menu.entryconfig(index, accelerator=accel)

    def set_notabs_indentwidth(self):
        "Update the indentwidth if changed and not using tabs in this window"
        # Called from configdialog.py
        if not self.usetabs:
            self.indentwidth = idleConf.GetOption('main', 'Indent','num-spaces',
                                                  type='int')

    def reset_help_menu_entries(self):
        "Update the additional help entries on the Help menu"
        help_list = idleConf.GetAllExtraHelpSourcesList()
        helpmenu = self.menudict['help']
        # first delete the extra help entries, if any
        helpmenu_length = helpmenu.index(END)
        if helpmenu_length > self.base_helpmenu_length:
            helpmenu.delete((self.base_helpmenu_length + 1), helpmenu_length)
        # then rebuild them
        if help_list:
            helpmenu.add_separator()
            for entry in help_list:
                cmd = self.__extra_help_callback(entry[1])
                helpmenu.add_command(label=entry[0], command=cmd)
        # and update the menu dictionary
        self.menudict['help'] = helpmenu

    def __extra_help_callback(self, helpfile):
        "Create a callback with the helpfile value frozen at definition time"
        def display_extra_help(helpfile=helpfile):
            if not helpfile.startswith(('www', 'http')):
                helpfile = os.path.normpath(helpfile)
            if sys.platform[:3] == 'win':
                try:
                    os.startfile(helpfile)
                except OSError as why:
                    tkMessageBox.showerror(title='Document Start Failure',
                        message=str(why), parent=self.text)
            else:
                webbrowser.open(helpfile)
        return display_extra_help

    def update_recent_files_list(self, new_file=None):
        "Load and update the recent files list and menus"
        rf_list = []
        if os.path.exists(self.recent_files_path):
            with open(self.recent_files_path, 'r',
                      encoding='utf_8', errors='replace') as rf_list_file:
                rf_list = rf_list_file.readlines()
        if new_file:
            new_file = os.path.abspath(new_file) + '\n'
            if new_file in rf_list:
                rf_list.remove(new_file)  # move to top
            rf_list.insert(0, new_file)
        # clean and save the recent files list
        bad_paths = []
        for path in rf_list:
            if '\0' in path or not os.path.exists(path[0:-1]):
                bad_paths.append(path)
        rf_list = [path for path in rf_list if path not in bad_paths]
        ulchars = "1234567890ABCDEFGHIJK"
        rf_list = rf_list[0:len(ulchars)]
        try:
            with open(self.recent_files_path, 'w',
                        encoding='utf_8', errors='replace') as rf_file:
                rf_file.writelines(rf_list)
        except OSError as err:
            if not getattr(self.root, "recentfilelist_error_displayed", False):
                self.root.recentfilelist_error_displayed = True
                tkMessageBox.showwarning(title='IDLE Warning',
                    message="Cannot update File menu Recent Files list. "
                            "Your operating system says:\n%s\n"
                            "Select OK and IDLE will continue without updating."
                        % self._filename_to_unicode(str(err)),
                    parent=self.text)
        # for each edit window instance, construct the recent files menu
        for instance in self.top.instance_dict:
            menu = instance.recent_files_menu
            menu.delete(0, END)  # clear, and rebuild:
            for i, file_name in enumerate(rf_list):
                file_name = file_name.rstrip()  # zap \n
                # make unicode string to display non-ASCII chars correctly
                ufile_name = self._filename_to_unicode(file_name)
                callback = instance.__recent_file_callback(file_name)
                menu.add_command(label=ulchars[i] + " " + ufile_name,
                                 command=callback,
                                 underline=0)

    def __recent_file_callback(self, file_name):
        def open_recent_file(fn_closure=file_name):
            self.io.open(editFile=fn_closure)
        return open_recent_file

    def saved_change_hook(self):
        short = self.short_title()
        long = self.long_title()
        if short and long:
            title = short + " - " + long + _py_version
        elif short:
            title = short
        elif long:
            title = long
        else:
            title = "untitled"
        icon = short or long or title
        if not self.get_saved():
            title = "*%s*" % title
            icon = "*%s" % icon
        self.top.wm_title(title)
        self.top.wm_iconname(icon)

    def get_saved(self):
        return self.undo.get_saved()

    def set_saved(self, flag):
        self.undo.set_saved(flag)

    def reset_undo(self):
        self.undo.reset_undo()

    def short_title(self):
        filename = self.io.filename
        if filename:
            filename = os.path.basename(filename)
        else:
            filename = "untitled"
        # return unicode string to display non-ASCII chars correctly
        return self._filename_to_unicode(filename)

    def long_title(self):
        # return unicode string to display non-ASCII chars correctly
        return self._filename_to_unicode(self.io.filename or "")

    def center_insert_event(self, event):
        self.center()
        return "break"

    def center(self, mark="insert"):
        text = self.text
        top, bot = self.getwindowlines()
        lineno = self.getlineno(mark)
        height = bot - top
        newtop = max(1, lineno - height//2)
        text.yview(float(newtop))

    def getwindowlines(self):
        text = self.text
        top = self.getlineno("@0,0")
        bot = self.getlineno("@0,65535")
        if top == bot and text.winfo_height() == 1:
            # Geometry manager hasn't run yet
            height = int(text['height'])
            bot = top + height - 1
        return top, bot

    def getlineno(self, mark="insert"):
        text = self.text
        return int(float(text.index(mark)))

    def get_geometry(self):
        "Return (width, height, x, y)"
        geom = self.top.wm_geometry()
        m = re.match(r"(\d+)x(\d+)\+(-?\d+)\+(-?\d+)", geom)
        return list(map(int, m.groups()))

    def close_event(self, event):
        self.close()
        return "break"

    def maybesave(self):
        if self.io:
            if not self.get_saved():
                if self.top.state()!='normal':
                    self.top.deiconify()
                self.top.lower()
                self.top.lift()
            return self.io.maybesave()

    def close(self):
        reply = self.maybesave()
        if str(reply) != "cancel":
            self._close()
        return reply

    def _close(self):
        if self.io.filename:
            self.update_recent_files_list(new_file=self.io.filename)
        window.unregister_callback(self.postwindowsmenu)
        self.unload_extensions()
        self.io.close()
        self.io = None
        self.undo = None
        if self.color:
            self.color.close()
            self.color = None
        self.text = None
        self.tkinter_vars = None
        self.per.close()
        self.per = None
        self.top.destroy()
        if self.close_hook:
            # unless override: unregister from flist, terminate if last window
            self.close_hook()

    def load_extensions(self):
        self.extensions = {}
        self.load_standard_extensions()

    def unload_extensions(self):
        for ins in list(self.extensions.values()):
            if hasattr(ins, "close"):
                ins.close()
        self.extensions = {}

    def load_standard_extensions(self):
        for name in self.get_standard_extension_names():
            try:
                self.load_extension(name)
            except:
                print("Failed to load extension", repr(name))
                traceback.print_exc()

    def get_standard_extension_names(self):
        return idleConf.GetExtensions(editor_only=True)

    extfiles = {  # Map built-in config-extension section names to file names.
        'ZzDummy': 'zzdummy',
        }

    def load_extension(self, name):
        fname = self.extfiles.get(name, name)
        try:
            try:
                mod = importlib.import_module('.' + fname, package=__package__)
            except (ImportError, TypeError):
                mod = importlib.import_module(fname)
        except ImportError:
            print("\nFailed to import extension: ", name)
            raise
        cls = getattr(mod, name)
        keydefs = idleConf.GetExtensionBindings(name)
        if hasattr(cls, "menudefs"):
            self.fill_menus(cls.menudefs, keydefs)
        ins = cls(self)
        self.extensions[name] = ins
        if keydefs:
            self.apply_bindings(keydefs)
            for vevent in keydefs:
                methodname = vevent.replace("-", "_")
                while methodname[:1] == '<':
                    methodname = methodname[1:]
                while methodname[-1:] == '>':
                    methodname = methodname[:-1]
                methodname = methodname + "_event"
                if hasattr(ins, methodname):
                    self.text.bind(vevent, getattr(ins, methodname))

    def apply_bindings(self, keydefs=None):
        if keydefs is None:
            keydefs = self.mainmenu.default_keydefs
        text = self.text
        text.keydefs = keydefs
        for event, keylist in keydefs.items():
            if keylist:
                text.event_add(event, *keylist)

    def fill_menus(self, menudefs=None, keydefs=None):
        """Add appropriate entries to the menus and submenus

        Menus that are absent or None in self.menudict are ignored.
        """
        if menudefs is None:
            menudefs = self.mainmenu.menudefs
        if keydefs is None:
            keydefs = self.mainmenu.default_keydefs
        menudict = self.menudict
        text = self.text
        for mname, entrylist in menudefs:
            menu = menudict.get(mname)
            if not menu:
                continue
            for entry in entrylist:
                if not entry:
                    menu.add_separator()
                else:
                    label, eventname = entry
                    checkbutton = (label[:1] == '!')
                    if checkbutton:
                        label = label[1:]
                    underline, label = prepstr(label)
                    accelerator = get_accelerator(keydefs, eventname)
                    def command(text=text, eventname=eventname):
                        text.event_generate(eventname)
                    if checkbutton:
                        var = self.get_var_obj(eventname, BooleanVar)
                        menu.add_checkbutton(label=label, underline=underline,
                            command=command, accelerator=accelerator,
                            variable=var)
                    else:
                        menu.add_command(label=label, underline=underline,
                                         command=command,
                                         accelerator=accelerator)

    def getvar(self, name):
        var = self.get_var_obj(name)
        if var:
            value = var.get()
            return value
        else:
            raise NameError(name)

    def setvar(self, name, value, vartype=None):
        var = self.get_var_obj(name, vartype)
        if var:
            var.set(value)
        else:
            raise NameError(name)

    def get_var_obj(self, name, vartype=None):
        var = self.tkinter_vars.get(name)
        if not var and vartype:
            # create a Tkinter variable object with self.text as master:
            self.tkinter_vars[name] = var = vartype(self.text)
        return var

    # Tk implementations of "virtual text methods" -- each platform
    # reusing IDLE's support code needs to define these for its GUI's
    # flavor of widget.

    # Is character at text_index in a Python string?  Return 0 for
    # "guaranteed no", true for anything else.  This info is expensive
    # to compute ab initio, but is probably already known by the
    # platform's colorizer.

    def is_char_in_string(self, text_index):
        if self.color:
            # Return true iff colorizer hasn't (re)gotten this far
            # yet, or the character is tagged as being in a string
            return self.text.tag_prevrange("TODO", text_index) or \
                   "STRING" in self.text.tag_names(text_index)
        else:
            # The colorizer is missing: assume the worst
            return 1

    # If a selection is defined in the text widget, return (start,
    # end) as Tkinter text indices, otherwise return (None, None)
    def get_selection_indices(self):
        try:
            first = self.text.index("sel.first")
            last = self.text.index("sel.last")
            return first, last
        except TclError:
            return None, None

    # Return the text widget's current view of what a tab stop means
    # (equivalent width in spaces).

    def get_tk_tabwidth(self):
        current = self.text['tabs'] or TK_TABWIDTH_DEFAULT
        return int(current)

    # Set the text widget's current view of what a tab stop means.

    def set_tk_tabwidth(self, newtabwidth):
        text = self.text
        if self.get_tk_tabwidth() != newtabwidth:
            # Set text widget tab width
            pixels = text.tk.call("font", "measure", text["font"],
                                  "-displayof", text.master,
                                  "n" * newtabwidth)
            text.configure(tabs=pixels)

### begin autoindent code ###  (configuration was moved to beginning of class)

    def set_indentation_params(self, is_py_src, guess=True):
        if is_py_src and guess:
            i = self.guess_indent()
            if 2 <= i <= 8:
                self.indentwidth = i
            if self.indentwidth != self.tabwidth:
                self.usetabs = False
        self.set_tk_tabwidth(self.tabwidth)

    def smart_backspace_event(self, event):
        text = self.text
        first, last = self.get_selection_indices()
        if first and last:
            text.delete(first, last)
            text.mark_set("insert", first)
            return "break"
        # Delete whitespace left, until hitting a real char or closest
        # preceding virtual tab stop.
        chars = text.get("insert linestart", "insert")
        if chars == '':
            if text.compare("insert", ">", "1.0"):
                # easy: delete preceding newline
                text.delete("insert-1c")
            else:
                text.bell()     # at start of buffer
            return "break"
        if  chars[-1] not in " \t":
            # easy: delete preceding real char
            text.delete("insert-1c")
            return "break"
        # Ick.  It may require *inserting* spaces if we back up over a
        # tab character!  This is written to be clear, not fast.
        tabwidth = self.tabwidth
        have = len(chars.expandtabs(tabwidth))
        assert have > 0
        want = ((have - 1) // self.indentwidth) * self.indentwidth
        # Debug prompt is multilined....
        ncharsdeleted = 0
        while 1:
            if chars == self.prompt_last_line:  # '' unless PyShell
                break
            chars = chars[:-1]
            ncharsdeleted = ncharsdeleted + 1
            have = len(chars.expandtabs(tabwidth))
            if have <= want or chars[-1] not in " \t":
                break
        text.undo_block_start()
        text.delete("insert-%dc" % ncharsdeleted, "insert")
        if have < want:
            text.insert("insert", ' ' * (want - have))
        text.undo_block_stop()
        return "break"

    def smart_indent_event(self, event):
        # if intraline selection:
        #     delete it
        # elif multiline selection:
        #     do indent-region
        # else:
        #     indent one level
        text = self.text
        first, last = self.get_selection_indices()
        text.undo_block_start()
        try:
            if first and last:
                if index2line(first) != index2line(last):
                    return self.fregion.indent_region_event(event)
                text.delete(first, last)
                text.mark_set("insert", first)
            prefix = text.get("insert linestart", "insert")
            raw, effective = get_line_indent(prefix, self.tabwidth)
            if raw == len(prefix):
                # only whitespace to the left
                self.reindent_to(effective + self.indentwidth)
            else:
                # tab to the next 'stop' within or to right of line's text:
                if self.usetabs:
                    pad = '\t'
                else:
                    effective = len(prefix.expandtabs(self.tabwidth))
                    n = self.indentwidth
                    pad = ' ' * (n - effective % n)
                text.insert("insert", pad)
            text.see("insert")
            return "break"
        finally:
            text.undo_block_stop()

    def newline_and_indent_event(self, event):
        text = self.text
        first, last = self.get_selection_indices()
        text.undo_block_start()
        try:
            if first and last:
                text.delete(first, last)
                text.mark_set("insert", first)
            line = text.get("insert linestart", "insert")
            i, n = 0, len(line)
            while i < n and line[i] in " \t":
                i = i+1
            if i == n:
                # the cursor is in or at leading indentation in a continuation
                # line; just inject an empty line at the start
                text.insert("insert linestart", '\n')
                return "break"
            indent = line[:i]
            # strip whitespace before insert point unless it's in the prompt
            i = 0
            while line and line[-1] in " \t" and line != self.prompt_last_line:
                line = line[:-1]
                i = i+1
            if i:
                text.delete("insert - %d chars" % i, "insert")
            # strip whitespace after insert point
            while text.get("insert") in " \t":
                text.delete("insert")
            # start new line
            text.insert("insert", '\n')

            # adjust indentation for continuations and block
            # open/close first need to find the last stmt
            lno = index2line(text.index('insert'))
            y = pyparse.Parser(self.indentwidth, self.tabwidth)
            if not self.prompt_last_line:
                for context in self.num_context_lines:
                    startat = max(lno - context, 1)
                    startatindex = repr(startat) + ".0"
                    rawtext = text.get(startatindex, "insert")
                    y.set_code(rawtext)
                    bod = y.find_good_parse_start(
                              self._build_char_in_string_func(startatindex))
                    if bod is not None or startat == 1:
                        break
                y.set_lo(bod or 0)
            else:
                r = text.tag_prevrange("console", "insert")
                if r:
                    startatindex = r[1]
                else:
                    startatindex = "1.0"
                rawtext = text.get(startatindex, "insert")
                y.set_code(rawtext)
                y.set_lo(0)

            c = y.get_continuation_type()
            if c != pyparse.C_NONE:
                # The current stmt hasn't ended yet.
                if c == pyparse.C_STRING_FIRST_LINE:
                    # after the first line of a string; do not indent at all
                    pass
                elif c == pyparse.C_STRING_NEXT_LINES:
                    # inside a string which started before this line;
                    # just mimic the current indent
                    text.insert("insert", indent)
                elif c == pyparse.C_BRACKET:
                    # line up with the first (if any) element of the
                    # last open bracket structure; else indent one
                    # level beyond the indent of the line with the
                    # last open bracket
                    self.reindent_to(y.compute_bracket_indent())
                elif c == pyparse.C_BACKSLASH:
                    # if more than one line in this stmt already, just
                    # mimic the current indent; else if initial line
                    # has a start on an assignment stmt, indent to
                    # beyond leftmost =; else to beyond first chunk of
                    # non-whitespace on initial line
                    if y.get_num_lines_in_stmt() > 1:
                        text.insert("insert", indent)
                    else:
                        self.reindent_to(y.compute_backslash_indent())
                else:
                    assert 0, "bogus continuation type %r" % (c,)
                return "break"

            # This line starts a brand new stmt; indent relative to
            # indentation of initial line of closest preceding
            # interesting stmt.
            indent = y.get_base_indent_string()
            text.insert("insert", indent)
            if y.is_block_opener():
                self.smart_indent_event(event)
            elif indent and y.is_block_closer():
                self.smart_backspace_event(event)
            return "break"
        finally:
            text.see("insert")
            text.undo_block_stop()

    # Our editwin provides an is_char_in_string function that works
    # with a Tk text index, but PyParse only knows about offsets into
    # a string. This builds a function for PyParse that accepts an
    # offset.

    def _build_char_in_string_func(self, startindex):
        def inner(offset, _startindex=startindex,
                  _icis=self.is_char_in_string):
            return _icis(_startindex + "+%dc" % offset)
        return inner

    # XXX this isn't bound to anything -- see tabwidth comments
##     def change_tabwidth_event(self, event):
##         new = self._asktabwidth()
##         if new != self.tabwidth:
##             self.tabwidth = new
##             self.set_indentation_params(0, guess=0)
##         return "break"

    # Make string that displays as n leading blanks.

    def _make_blanks(self, n):
        if self.usetabs:
            ntabs, nspaces = divmod(n, self.tabwidth)
            return '\t' * ntabs + ' ' * nspaces
        else:
            return ' ' * n

    # Delete from beginning of line to insert point, then reinsert
    # column logical (meaning use tabs if appropriate) spaces.

    def reindent_to(self, column):
        text = self.text
        text.undo_block_start()
        if text.compare("insert linestart", "!=", "insert"):
            text.delete("insert linestart", "insert")
        if column:
            text.insert("insert", self._make_blanks(column))
        text.undo_block_stop()

    # Guess indentwidth from text content.
    # Return guessed indentwidth.  This should not be believed unless
    # it's in a reasonable range (e.g., it will be 0 if no indented
    # blocks are found).

    def guess_indent(self):
        opener, indented = IndentSearcher(self.text, self.tabwidth).run()
        if opener and indented:
            raw, indentsmall = get_line_indent(opener, self.tabwidth)
            raw, indentlarge = get_line_indent(indented, self.tabwidth)
        else:
            indentsmall = indentlarge = 0
        return indentlarge - indentsmall

    def toggle_line_numbers_event(self, event=None):
        if self.line_numbers is None:
            return

        if self.line_numbers.is_shown:
            self.line_numbers.hide_sidebar()
            menu_label = "Show"
        else:
            self.line_numbers.show_sidebar()
            menu_label = "Hide"
        self.update_menu_label(menu='options', index='*Line Numbers',
                               label=f'{menu_label} Line Numbers')

# "line.col" -> line, as an int
def index2line(index):
    return int(float(index))


_line_indent_re = re.compile(r'[ \t]*')
def get_line_indent(line, tabwidth):
    """Return a line's indentation as (# chars, effective # of spaces).

    The effective # of spaces is the length after properly "expanding"
    the tabs into spaces, as done by str.expandtabs(tabwidth).
    """
    m = _line_indent_re.match(line)
    return m.end(), len(m.group().expandtabs(tabwidth))


class IndentSearcher(object):

    # .run() chews over the Text widget, looking for a block opener
    # and the stmt following it.  Returns a pair,
    #     (line containing block opener, line containing stmt)
    # Either or both may be None.

    def __init__(self, text, tabwidth):
        self.text = text
        self.tabwidth = tabwidth
        self.i = self.finished = 0
        self.blkopenline = self.indentedline = None

    def readline(self):
        if self.finished:
            return ""
        i = self.i = self.i + 1
        mark = repr(i) + ".0"
        if self.text.compare(mark, ">=", "end"):
            return ""
        return self.text.get(mark, mark + " lineend+1c")

    def tokeneater(self, type, token, start, end, line,
                   INDENT=tokenize.INDENT,
                   NAME=tokenize.NAME,
                   OPENERS=('class', 'def', 'for', 'if', 'try', 'while')):
        if self.finished:
            pass
        elif type == NAME and token in OPENERS:
            self.blkopenline = line
        elif type == INDENT and self.blkopenline:
            self.indentedline = line
            self.finished = 1

    def run(self):
        save_tabsize = tokenize.tabsize
        tokenize.tabsize = self.tabwidth
        try:
            try:
                tokens = tokenize.generate_tokens(self.readline)
                for token in tokens:
                    self.tokeneater(*token)
            except (tokenize.TokenError, SyntaxError):
                # since we cut off the tokenizer early, we can trigger
                # spurious errors
                pass
        finally:
            tokenize.tabsize = save_tabsize
        return self.blkopenline, self.indentedline

### end autoindent code ###

def prepstr(s):
    # Helper to extract the underscore from a string, e.g.
    # prepstr("Co_py") returns (2, "Copy").
    i = s.find('_')
    if i >= 0:
        s = s[:i] + s[i+1:]
    return i, s


keynames = {
 'bracketleft': '[',
 'bracketright': ']',
 'slash': '/',
}

def get_accelerator(keydefs, eventname):
    keylist = keydefs.get(eventname)
    # issue10940: temporary workaround to prevent hang with OS X Cocoa Tk 8.5
    # if not keylist:
    if (not keylist) or (macosx.isCocoaTk() and eventname in {
                            "<<open-module>>",
                            "<<goto-line>>",
                            "<<change-indentwidth>>"}):
        return ""
    s = keylist[0]
    s = re.sub(r"-[a-z]\b", lambda m: m.group().upper(), s)
    s = re.sub(r"\b\w+\b", lambda m: keynames.get(m.group(), m.group()), s)
    s = re.sub("Key-", "", s)
    s = re.sub("Cancel","Ctrl-Break",s)   # dscherer@cmu.edu
    s = re.sub("Control-", "Ctrl-", s)
    s = re.sub("-", "+", s)
    s = re.sub("><", " ", s)
    s = re.sub("<", "", s)
    s = re.sub(">", "", s)
    return s


def fixwordbreaks(root):
    # On Windows, tcl/tk breaks 'words' only on spaces, as in Command Prompt.
    # We want Motif style everywhere. See #21474, msg218992 and followup.
    tk = root.tk
    tk.call('tcl_wordBreakAfter', 'a b', 0) # make sure word.tcl is loaded
    tk.call('set', 'tcl_wordchars', r'\w')
    tk.call('set', 'tcl_nonwordchars', r'\W')


def _editor_window(parent):  # htest #
    # error if close master window first - timer event, after script
    root = parent
    fixwordbreaks(root)
    if sys.argv[1:]:
        filename = sys.argv[1]
    else:
        filename = None
    macosx.setupApp(root, None)
    edit = EditorWindow(root=root, filename=filename)
    text = edit.text
    text['height'] = 10
    for i in range(20):
        text.insert('insert', '  '*i + str(i) + '\n')
    # text.bind("<<close-all-windows>>", edit.close_event)
    # Does not stop error, neither does following
    # edit.text.bind("<<close-window>>", edit.close_event)

if __name__ == '__main__':
    from unittest import main
    main('idlelib.idle_test.test_editor', verbosity=2, exit=False)

    from idlelib.idle_test.htest import run
    run(_editor_window)